Boxster 986 Autocross/Track Setup

[03boxster-S]

Yeah i found a track event near me via PCA but its at Virginia Int'l Raceway which requires the Boxster to have the rollbar extension

[Bill Ladd]

It’s my understanding that VIR requires a rollbar extension on Boxsters. Can’t remember where I read that though (Hurricane Chapter newsletter? Here? VIR website?), but after reading it I went ahead and got a Brey Krause.

[Topless]

Originally Posted by lawren

Still hoping to get an answer to the following questions:

1. Should i do a front or rear adjustable sway bar with stock shocks/struts? Or should i do both? Or should i do neither?
2. Will 235 fit on front or is 225 the max with LCAs and stock struts?

I ran 255/255 square for a year on stock struts and 8.5/17" wheels. They will fit. If you roll the fenders you can mount 285/285 square.

[lawren]

I have my first autocross and track day of the season in a few weeks. I was wondering if someone could give me some tire pressure recommendations. This is the setup that I will be starting out with:

Car
1998 Boxster Base Model (2.5L)
Manual with Aero Package

SCCA Autocross STR Class Setup:
Stock 17"x 7" fronts and 17"x 8.5" rear wheels
Bridgestone RE71Rs (225/45-17 front & 255/40-17 rear)
Front LCA (this is my only suspension mod at this point)
Carbotech xp8 brake pads (or should I stick with stock for autocross?)

Track Setup (same as above with following additions/changes):
OZ 18"x8.5" fronts and 18"x10" rear wheels
Toyo R888Rs (235/45-18 front & 265/35-18 Rear)

[lawren]

I have my first autocross and track day of the season in a few weeks. I was wondering if someone could give me some tire pressure recommendations. This is the setup that I will be starting out with:

Car
1998 Boxster Base Model (2.5L)
Manual with Aero Package

SCCA Autocross STR Class Setup:
Stock 17"x 7" fronts and 17"x 8.5" rear wheels
Bridgestone RE71Rs (225/45-17 front & 255/40-17 rear)
Front LCA (this is my only suspension mod at this point)
Carbotech xp8 brake pads (or should I stick with stock for autocross?)

Track Setup (same as above with following additions/changes):
OZ 18"x8.5" fronts and 18"x10" rear wheels
Toyo R888Rs (235/45-18 front & 265/35-18 Rear)

[Anker]

For the RE71-Rs the best tire pressure is just over 30 PSI front and back. Fine tune it by chalking your tires. Check the pressure after each run to compensate for heating.

I have not run Toyo R888Rs on track, but have tracked RE71-Rs and found that they overheated. Suggest you start with a fairly high pressure, like 34 PSI front and back and measure tire temperature with a tire pyrometer after the tires have warmed up. For the Toyos they publish a recommended temperature range. If the tire gets too hot raise the pressure, if too cool, lower it.

[lawren]

I've had both my first autocross and track day weekends in the Boxster. My setup is as mentioned below in previous post but i thought i would include the following:

SPC LCAs in front. Front camber is set at about -3 each side. Camber is set to max stock setting in rear. No adjustable anti-roll bars (yet). No toe links in rear (yet).

Here are my initial impressions:

Autocross
Positive: Balance was awesome!! I just kept ramping up the speed in the longer sweepers until I started to get a four wheel drift. They also had a skid pad element set up in the course and I didn't get as much understeer there as i was expecting. I'm sure that was the result of the increased camber in the front. Kept lowering the pressures in the RE71Rs until i was rolling over to the tips of the triangles on all four tires. Not surprisingly, when i got there i was getting my fastest times - that occurred right at about 30psi. That will be the pressures i am shooting for from now on. This car will be competitive at the local (and regional?) level in STR class.
Negative: Started to get a roaring noise in the turns (both directions) at the end of the first of the two-day weekend. Noise continued through second day. At first I suspected tire rub but quickly eliminated that. Suspected it was a wheel bearing but those checked out OK later by mechanic. Mechanic said he heard some noise in the gearbox/diff and changed the fluid (no debris). That certainly seemed to help with the noise (see below).

Track Day at Hallett the Next Weekend
Positive: Not much i can say here. The only positive was that the roaring noise did not reappear. It appears that the fluid change helped. However, I never really stressed the car like i did on the autocross day because of the conditions (rain).
Negative: The day was fun but it rained and the track was wet all day. I had no grip and had lost a lot of confidence in the car by the end of the day!! Tried both the new R888Rs and RE71Rs but neither was better than the other in the wet. The rear end was squirrely, especially if the rear became unweighted cresting a hill and going into a corner. Rear end also felt unstable under heavy braking just before turn in. It seemed like the car was going to come around on me under heavy braking.

Question: Did the rainy conditions expose an issue with the car? Could it be a bad rear toe setting? Could the roaring noise be a problem with the diff that is creating traction issues? I've done quite a few track days (dry and wet) in the past in my 997 and never had any issues like this.

Also, I find it a lot harder to heel-toe in this car. The bite in the brakes occurs very high in the brake pedal travel and I'm having difficulty rolling my foot far enough for the throttle blip. The throttle pedal is quite a ways below the brake pedal (even when really standing on it) and the result is unsteady brake pressure as i am trying to roll my foot way over. Are there adjustments that can be made?

[Handlebar]

Originally Posted by 03boxster-S

Yeah i found a track event near me via PCA but its at Virginia Int'l Raceway which requires the Boxster to have the rollbar extension

VIR is the only HPDE Track that we have run into this difference of opinion/requirement with.

Once things are running again, check out PCAPotomac.org - likely your home region, or a neighbor. If you are in DC to Richmond area, you may consider Summit Point, WV.

[spendy]

The height of the brake pedal can be adjusted, but you may find on a dry day with more traction that the pedal will drop a bit due to heat.
If you run brake pads with more bite on the rear that will help stabilize it. More rear toe can help too.

[1thenaton1]

You've got all this money in wheels and tires and are running on the track with blown out stock suspension? Don't exactly follow your thought process there. I'd find some decent coilovers.

Heel toe is super easy in these cars. Use your heel on the accelerator by rotating it outward. The pedal coming up from the floor instead of down from the top really makes heel toe easier by a large factor compared to other street cars

[thstone]

Originally Posted by lawren

Question: Did the rainy conditions expose an issue with the car? Could it be a bad rear toe setting? Could the roaring noise be a problem with the diff that is creating traction issues? I've done quite a few track days (dry and wet) in the past in my 997 and never had any issues like this.

You just discovered the difference between 50/50 weight balance in the Boxster and 62/38 in the 997. The 997 carries a lot more weight over the (larger) rear wheels which help to keep it planted.

If the Boxster rear is too loose, you might want to adjust the sway bars to better balance the handling. But I would wait until you get a chance to try it on a dry track.

Tires also make a huge difference in the rain. I never thought of either of the tires you used as optimized for wet traction.

Originally Posted by lawren

Also, I find it a lot harder to heel-toe in this car. The bite in the brakes occurs very high in the brake pedal travel and I'm having difficulty rolling my foot far enough for the throttle blip. The throttle pedal is quite a ways below the brake pedal (even when really standing on it) and the result is unsteady brake pressure as i am trying to roll my foot way over. Are there adjustments that can be made?

I had the same problem so I installed a set of Rennline pedal covers and accelerator pedal extension and height adjustor. This made it 10x easier for me to heel/toe. YMMV.

[trygve]

Originally Posted by lawren

...
Negative: Started to get a roaring noise in the turns (both directions) at the end of the first of the two-day weekend. Noise continued through second day. At first I suspected tire rub but quickly eliminated that. Suspected it was a wheel bearing but those checked out OK later by mechanic. Mechanic said he heard some noise in the gearbox/diff and changed the fluid (no debris). That certainly seemed to help with the noise (see below).
...

If the noise occurred in both turning directions, it's unlikely to be a wheel bearing -- it usually makes noise when turning in the direction that puts weight on that wheel. One surprising thing that can cause a grinding/roaring noise when doing a hard turn is the engine mount (or possibly transmission mount). When it goes bad, it can cause the engine to move just enough to allow something to rub heat shielding or other things, and it sounds horrible!

The other things I thought of when you described instability in the wet, with unwanted rear end movement under braking, are alignment and stiffness. If you have too much (relative) front end grip and toe out, the front will be very happy under braking and turn-in, but the rear will not. Unwanted rear toe out will also be problematic, causing the rear of the car to be unstable under braking. And in the wet you really have to soften the rear end relative to the front, so that the rear of the car is "compliant" and grippy--you might consider disconnecting one side of the rear sway bar so it is effectively removed from the car. This will keep the rear end more planted, which is vital in the wet.

[lawren]

Thanks to everyone for your input. Please keep the suggestions coming. I'm trying to get this car figured out!

Originally Posted by 1thenaton1

You've got all this money in wheels and tires and are running on the track with blown out stock suspension? Don't exactly follow your thought process there. I'd find some decent coilovers.

Heel toe is super easy in these cars. Use your heel on the accelerator by rotating it outward. The pedal coming up from the floor instead of down from the top really makes heel toe easier by a large factor compared to other street cars

I don't have coilovers but the car came with suspension that was recently upgraded to higher performance Bilsteins and they seem to be performing well. I have always assumed that the first upgrade that everyone should make is a decent set of tires!! Is that not true? FYI - new coilovers are planned for the near future.

Since that track day in the rain, i've been practicing heel-toe on the street and it's getting better but still not nearly as easy as the 997 especially with the race pads and that crazy initial bite. I think i'm going with the Rennline pedal cover suggestion.

Originally Posted by thstone

You just discovered the difference between 50/50 weight balance in the Boxster and 62/38 in the 997. The 997 carries a lot more weight over the (larger) rear wheels which help to keep it planted.

If the Boxster rear is too loose, you might want to adjust the sway bars to better balance the handling. But I would wait until you get a chance to try it on a dry track.

Tires also make a huge difference in the rain. I never thought of either of the tires you used as optimized for wet traction.

I had the same problem so I installed a set of Rennline pedal covers and accelerator pedal extension and height adjustor. This made it 10x easier for me to heel/toe. YMMV.

I'm looking forward to getting out there on a dry track to see what happens. I can tell that i'm going to love the car by the way that it drives on the street but that first track day experience in the wet was a little discouraging.

Like i said above, i'm going with the Rennline pedal covers.

Originally Posted by trygve

If the noise occurred in both turning directions, it's unlikely to be a wheel bearing -- it usually makes noise when turning in the direction that puts weight on that wheel. One surprising thing that can cause a grinding/roaring noise when doing a hard turn is the engine mount (or possibly transmission mount). When it goes bad, it can cause the engine to move just enough to allow something to rub heat shielding or other things, and it sounds horrible!

The other things I thought of when you described instability in the wet, with unwanted rear end movement under braking, are alignment and stiffness. If you have too much (relative) front end grip and toe out, the front will be very happy under braking and turn-in, but the rear will not. Unwanted rear toe out will also be problematic, causing the rear of the car to be unstable under braking. And in the wet you really have to soften the rear end relative to the front, so that the rear of the car is "compliant" and grippy--you might consider disconnecting one side of the rear sway bar so it is effectively removed from the car. This will keep the rear end more planted, which is vital in the wet.

Never thought about the engine or transmission mounts. I will give it a look. It is a horrible noise and i heard it again the other day during some spirited driving on the street.

I'm going to have the rear toe looked at soon but will probably leave any other adjustments until i get a chance to got to the track in the dry.